Such clamps are used in large numbers of pieces in container treating or transporting devices so as to temporarily grip and position containers, such as bottles, e.g. PET bottles. A firm seat of the container in the clamp is an important precondition for a smooth operation of the devices. Since the grip width of the containers can vary and since each container must be held independently of the existing grip width in an equally neatly centered way, clamps are used that are controlled between an opened insertion position and a closed gripping position, and in which elastic members are contained for compensating for such grip width variations.
WO 2006/102983 A refers to a clamp in which the closing levers formed in one piece with the gripping arms are directly acting on the closing cams. The elastic deformation areas are integrated into the closing levers, each time between the axis and the free end. The force accumulator consists of two mutually repelling permanent magnets at the axis side facing the gripping structures and acts on the gripping arms in the opening direction of the clamp. The closing cam has, for instance, an oval cross-section. In a rotary position of the closing cam the closing levers converge to a maximum degree under the action of the force accumulator whereas in another rotary position the gripping structures are moved towards each other and a container inserted between the gripping structures is retained. The rotary position of the closing cam defines the closing force acting on the container, in cooperation with the elasticity of the deformation area. The elasticity of the deformation area compensates for grip width variations. Since the deformation areas must absorb not only the loads needed for compensating for grip width variations, but must transmit all loads from the closing cam up to the gripping structures, fatigue breaks may occur. The reason is that excessive forces might act on the deformation area, e.g. when a container to be gripped is misaligned and/or eccentrically stuck due to outside influences, or if another obstacle blocks the closing movement of one or both gripping arms.
DE-299 15 297 U refers to a clamp in the case of which curved leaf springs are positioned in the closing levers of both gripping arms and abut on the closing cam. The leaf springs are seated with a play in the press direction of the closing cam in recesses of the closing lever, with a pressure spring being used behind each spring leaf. This spring assembly serves to compensate for grip width variations of the container. The structure is of a multipart type. Furthermore, a plurality of narrow and undercut cavities are present, so that it is difficult to clean the clamps. Since every spring assembly is subject not only to deformations for compensating for grip width variations, but must transmit all forces between the closing cam and the gripping arm, fatigue breaks may occur or, in cases of emergency, excessive forces may act on the spring assemblies until these get into abutment, with at least the pressure springs getting easily damaged in this process.